Replace Alpine by minideb as initContainer in documentation (#15227)

Signed-off-by: Carlos Rodriguez Hernandez <crhernandez@bitnami.com>

stable/mariadb/Chart.yaml

@@ -1,6 +1,6 @@
 apiVersion: v1
 name: mariadb
-version: 6.5.3
+version: 6.5.4
 appVersion: 10.3.16
 description: Fast, reliable, scalable, and easy to use open-source relational database system. MariaDB Server is intended for mission-critical, heavy-load production systems as well as for embedding into mass-deployed software. Highly available MariaDB cluster.
 keywords:

stable/mariadb/README.md

@@ -237,10 +237,10 @@ The feature allows for specifying a template string for a initContainer in the m
 master:
   extraInitContainers: |
     - name: initcontainer
-      image: alpine:latest
+      image: bitnami/minideb:latest
       command: ["/bin/sh", "-c"]
       args:
-        - curl http://api-service.local/db/starting;
+        - install_packages curl && curl http://api-service.local/db/starting;
 ```
 
 ## Upgrading